Here's a step-by-step for creating a pluggable brain. Create at .py module in your Extensions/ directory. For example create the following OrderLine.py file. class OrderLineClass:   """A simple pluggable brain example for an order line."""   def subtotal(self):     return self.quantity * self.amount Create an ZSQLMethod, named order_line_query, using the following SQL:   select item, quantity, amount from order_line Click on the 'Advanced' tab for the ZSQLMethod, enter the name of the module as 'OrderLine.py' and the name of the class as 'OrderLineClass'. Effectively, this class will become a mixin class for the object returned from the ZSQLMethod. Not only can you access each column of each row of the ZSQLMethod method as an attribute of an instance of the order_line_query class -- as this is the functionality of ZSQLMethods -- but, you can use the methods defined in the associated python module. Here is how this looks from DTML: <dtml-in order_line_query>
  Item: <dtml-var item>
  Qty: <dtml-var quantity>
  Amt: <dtml-var amount>
  Sub: <dtml-var subtotal>
</dtml-in>
For more information on ZSQLMethods, see the ZSQLMethods documentation. http://www.zope.org/Documentation/Guides/ZSQL/